Question

MCB (Miniautre circuit breaker)
works on the principle of magnetic effect of current? How?
How it disconnect circuit?

Answer 1

Miniature Circuit Breakers are safety switches used for protection of appliances and human beings. If the current through a circuit exceeds the safety limits rated by the MCB, it automatically turns off and protects the devices connected to the circuit. MCBs are the replacement for safety fuses used in earlier days.
i.e. MCB (Miniature Circuit Breaker) is an electronic device that detect fault in electrical connectivity and prevents short circuit by by discontinuing current flow in the household circuitry, or the switch trips and circuit is broken. Unlike an electrical fuse, we don't have to replace the MCB every time it breaks the circuit.
MCB consists of an electromagnet. If the current exceeds the rating of the circuit-breaker the pulling force of the magnet attracts an iron latch which breaks the electrical contacts.